Connecting means



June 23, 1936. H. A. DOUGLAS CONNECTING MEANS Filed Oct. 14, 1932 Harry CZ. pouyzaa Patented June 23, 1936 UNITED STATES autism PATENT OFFICE 1 Claim.

This invention relates to connecting means more particularly for electrical conductors, and, among other objects, aims to provide simple and improved means by which a lead may be con- 5 nected with the ordinary screw-threaded stud of a spark plug electrode, for example, without any change in the structure of the electrode, and without the addition of any parts thereto.

The invention will be understood by reference 10 to the illustrative embodiment thereof shown in the accompanying drawing, in which- Figure 1 is an end elevation of a portion of a spark plug with my invention applied thereto;

Figure 2 is a section taken on the line 2-2 of 15 Figure 1;

Figure 3 is an enlarged fragmentary view of the spark plug stud and my improved jack therefor;

Figure 4 shows a modified form of jack; and

20 Figure 5 is a cross-section taken on the line ,5-5 of Figure 4.

Referring in detail to the figures of the drawing I have shown a portion of a conventional spark plug I for an internal combustion engine, for example, said plug having the usual central electrode 2 which terminates at the top of the plug in a stud 2a, constituting the high tension terminal of the plug. As is customary this stud, in accordance with common practice, is screwthreaded as at 3 to have screwed thereon the usual clamping nut (not shown).

As the usual method of attaching a lead to thespark plug electrode 2 by the customary clamping nut referred to is objectionable, in that the nut jars loose, I have provided improved means by which this may be accomplished, by merely discarding the clamping nut referred to.

In accordance with my invention, the usual high voltage lead wire 4 having the heavy insulation thereon is connected by suitable means with my improved jack 6. As shown in Figure 2, the wire 4 may have a metallic tip I suitably secured thereto and exteriorly screw-threaded to be threadedly received in an axial recess such as the interiorly threaded socket 8 in the base 9 at one end of the jack 6, thus the jack and wire 4 are readily separable but firmly united. The tip I desirably has an enlarged sleeve portion I0 thereon which receives the insulation 5.

The jack 6 has a transverse aperture II therein intermediate the ends of the jack which is adapted to receive the member to be connected there-- to here represented by the screw-threaded stud 2a of the electrode 2, by a rectilinear movement as is well-known in snap terminal connections,

the aperture ll being slightly larger than the outside diameter of the stud 2a, means being provided for pressing the stud 2a and the jack 6 together to take up the play between the stud and the walls of the aperture I I, thus effecting a good 5 electrical connection.

Instead of having the usual smooth wall with the aperture H however, I provide, in accordance with my invention, a corrugated wall in this aperture against which the stud 2a is pressed so as 10 to provide not only a better electrical connection between the stud and the jack, but also a secure mechanical connection therebetween, all without any change in the structure of the stud and without the addition of any parts thereto, while at the same time retaining the advantages of a snap terminal in which the parts are moved into connected position by a simple rectilinear movement and are yieldingly but firmly held together.

As here shown I have provided the corrugated wall referred to in the aperture H by interiorly screw threading the aperture similarly to the standard screw-threaded structure 3 of the stud 2a, so far as the pitch of both of the threads are concerned, but with the threads l2 of the aperture l l of substantially less altitude than the threads 3 of the stud 211. That is to say, there are as many threads I2 to an inch as there are threads 3 to an inch, which may be, for example, thirty-two in both cases, in accordance with standard practice for the studs 2a. Since the threads 12, however, are of less altitude than the threads 3, the inclines In of the threads I2 will form between each other a greater or more obtuse angle than the inclines 3a of the threads 3. For example, if the inclines 311 form between each other an angle of 60 degrees, as shown in Figure 3, the inclines 12a may desirably form an angle of 120 degrees. Thus when the threads 3 0 are pressed against the threads I2 by the means presently described, the friction between the. parts will be enhanced by the threads, while at the same time the jack 6 may be placed telescopically over the stud 2a or separated therefrom by a pressure or pull as the case may be substantially less than any desired high pressure which may be employed to press the threads 3 and 12 together. In other words, the apices l3 of the threads l2 being of less altitude and approached by relatively more gradual inclines 12a will permit the apices [4 of the threads 3 to ride thereover, the gradual inclines I211 providing cam surfaces for the apices l4 and permitting the apices M to be yieldingly but firmly received 55 in the troughs l5 of the threads l2. To press the threads 3 and I2 together, I desirably employ a steel ball [6 which is revolubly carried by the jack 6 upon an annular tapered seat H in the interior l8 of a spring barrel l9 here shown formed integrally with the jack 6 and provided by axially recessing the outer end of the jack and then contracting the extremities of this outer end. The spring barrel l9 houses a coil spring 20 which presses at one end against the end of the barrel l9 and at its other end annularly upon the ball H3. The spring barrel I9 is arranged longitudinally of the jack 6 and transversely of the aperture H and an opening 2| margined by the seat I! permits the ball E6 to partially project into the aperture I l sufficiently, so that when the stud 2a and jack 6 are telescoped together the jack is moved upon the stud against the pressure of the spring 20 and with the threads 3 and. I2 in engagement throughout a substantial portion of the circumference of the stud 2a. The revoluble ball l6 which acts somewhat as a detent supplies a ball bearing action between the parts which facilitates engagement and separation thereof and at the same time permits a relatively high pressure to be exercised by the spring 20 to press the threads 3 and I2 together as described. I have found that a pressure of as much as thirty pounds, for example, may be advantageously transmitted by the spring 20 through the ball IE to the stud 2a and that with such pressure and with the relative proportions of the parts heretofore described, the parts may be engaged or separated with a pressure or pull as the case may be of approximately eleven pounds.

In Figures 4 and 5, I have shown a modified form of jack 22 which may be permanently secured to the lead wire 23 as by having the base 24 of the jack 22 receive the termination of the wire 23 in a recess 25 of the base, the base being thereafter swedged upon the wire by being indented as at 26 at desirably four points spaced about the axis of the wire, as best shown in Figure 5. The base 24 is shown sufficiently indented at the points 26 to contract the recess 25 as at 2'! sufficiently to distort and reduce the crosssectional area of the wire as at 28, thus substantially fusing the wire and plug. This latter structure is disclosed and claimed in my Patent No. 2,034,090. The base 24 may have a sleeve 29 permanently secured thereto for the same purpose as the sleeve [0.

Having described embodiments of my Invention, I claim:

In combination: an externally screw-threaded metallic stud; a conductor terminal for receiving said stud, said terminal comprising: a metallic portion having a recess; said recess having a diameter larger than said stud; biasing means including a movable wall portion for said recess biased toward a position to restrict said recess to a minimum diameter less than the diameter of said stud, for forcing said recess and said stud into eccentricity with each other with said stud in contact with a wall of said recess; and means so constructed and arranged that said conductor terminal Will be securely held on said stud, but assemblable with and disassemblable from said stud by assembling and disassembling forces applied to aid conductor terminal in the general direction of the axis of said recess while said biasing means forces said recess and said stud into said eccentric position, said means including screw-threads, in said recess, having the same direction and pitch as those on said stud but of less depth, said assembling and disassembling forces causing relative cam action between crests of the threads on said stud and sides of the threads of said recess so that said threads ride over each other in the general direction of the axis of the recess while under the bias of said biasing means.

HARRY A. DOUGLAS.

CERTIFICATE OF CORRECTION.

Patent No. 2,044,974. June 25, 1936.

HARRY A. DOUGLAS.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line 28, in the claim, for the word "aid" read said; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office Signed and sealed this 15th day of September, A. D. i936.

Henry Van Arsdale (Seal) Acting Commissioner of Patents. 

